Heater



FIG. 1 is a perspective view of the heater showing our new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a left-side elevational view thereof;

FIG. 4 is a right-side elevational view thereof;

FIG. 5 is a rear elevational view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The ornamental design for a heater, as shown and described.